Hey Mike,
I'm a structural engineer working out of RTP. I would imagine, if the house was originally built as a 3 story, the offset bearing wall condition was acounted for in the original design. That being said, I would be happy to come by one evening/ weekend and take a closer look at the situation with you.
Our office handles mainly commercial design, we used to know of a couple firms that dealt with the residential market in the area, but those firms have dwindled away in the past few years.
I will be out of town through Tuesday, (08/19), but if you would like me to come by one evening next week, shoot me a PM.
Enjoy the weekend,
